This invention relates to electroluminescent devices, such as electroluminescent diodes.
Electroluminescent diodes (or LED) are light emitting devices which are more and more used due to, especially, their low cost, low overall dimension, reliability, sturdiness and high output. These LEDs are used particularly in the fields of displaying, lighting and signalling when they emit in the visible spectrum, or in the field of remote control when they emit in infrared. They are generally made from a semiconductor material, especially of the III-V family, deposited on a substrate, solidarised to a base, and connected to two electrodes, the assembly being accomodated in an epoxy resin dome.
In order to improve the output of these LEDs, it has recently been suggested (see among others the U.S. Pat. No 5,405,710 document) to realise them in the form of stacking, wherein means of electron and hole generation and converting means of electron-hole pairs into photons are placed between a lower mirror (reflective), placed on a substrate, and an upper mirror (semi-reflective) parallel to the lower mirror and communicating with the outside. However, only the photons which are emitted in a significantly normal direction to the plane of the upper mirror and towards the latter, and photons which are emitted in a significantly normal direction to the plane of the lower mirror and towards the latter, are then reflected to the upper mirror, are able to reach the exterior of the device. Consequently, a not negligible part of the photons produced do not reach the exterior of the device.